[0001] The present invention relates to the field of face sealing annular valves for use
in fluid-working machines such as hydraulic pumps, hydraulic motors and hydraulic
pump-motors.
Background Art
[0002] It is known to use face sealing annular valves to regulate the flow of hydraulic
fluid into or out of a piston cylinder, or other working chamber of a fluid-working
machine. In annular valves of this type, a ring-shaped fluid path is selectively sealed
by a similarly ring-shaped annular valve member. Annular valves are advantageous as
they can provide a relatively large cross-sectional area through which hydraulic fluid
can flow into or out of a working chamber.
[0003] Face sealing annular valves comprise an annular valve member which is typically mounted
on a guide and they slide axially backward and forwards on the guide in use. However,
a known problem with face sealing annular valves is that the annular valve members
can jam in use if they tilt too far relative to the guide.
[0004] It is known to address this problem by providing annular valve members which are
relatively long compared to their radius. If the length/radius ratio is sufficiently
large, the annular valve member will not be able to tilt sufficiently far relative
to the guide for the annular valve member to jam. However, it is undesirable for annular
valve members to be long as this increases their mass and can increase the overall
size of the annular valve.
[0005] The problem may also be addressed by using an annular valve member which can only
move along a relatively short axial range and which has an inner diameter which is
significantly larger than the outer diameter of the guide. In this case, jamming is
unlikely, but the annular valve member can move significantly in a radial direction.
Without sufficient restriction on radial motion, it is difficult to form an effective
seal.
[0006] Therefore, the invention aims to provide an annular valve including an annular valve
member which does not jam in use and which has restricted radial motion to enable
a good seal to be formed. The invention also addresses the problems of keeping drag
and friction forces low to allow for rapid and efficient operation and aims to provide
an annular valve member with sufficient strength to withstand the stress of high pressure
oil acting on it in use.
Summary of Invention
[0007] According to a first aspect of the invention there is provided a face sealing annular
valve for a fluid working machine, the valve having a valve body arranged around a
central axis and comprising an annular valve seat and guide means (for example, a
guide) and an annular valve member located around or within the guide means;
the guide means comprising one or more cylindrically arranged guides to restrict radial
motion of the annular valve member;
the annular valve member arranged around an axis of symmetry and moveable axially
in relation to the guide means to sealedly engage with the annular valve seat; and
a guide engaging surface region extending around a circumference of the annular valve
member;
the annular valve member being configured so that, when the annular valve member and
the annular valve seat are coaxial, the spacing between the guide means and the guide-engaging
surface region increases with distance along the central axis from a minimum of spacing
between the annular valve member and the guide means according to claim 1.
[0008] The annular valve member may be retained around guide means, and when the annular
valve member and the annular valve seat are coaxial, the spacing between the guide
means and the guide-engaging surface region may increase with distance along the central
axis from a minimum inner circumference of the annular valve member. The annular valve
member may be retained within guide means and when the annular valve member and the
annular valve seat are coaxial, the spacing between the guide means and the guide-engaging
surface region may increase with distance along the central axis from a maximum outer
circumference of the annular valve member.
[0009] The annular valve seat may comprise an annular sealing surface and at least one aperture
providing a fluid pathway through the body associated with the or each said sealing
surface. In some embodiments, the annular valve seat may comprise more than one annular
sealing surface.
[0010] The annular valve member may comprise an annular seat-engaging surface (or in some
embodiments more than one annular seat-engaging surface, and in a preferred embodiment
two annular seat engaging surfaces) for sealing engagement with the or each sealing
surface. Accordingly, the annular valve member may be moveable in relation to the
guide means to sealedly engage the or each seat-engaging surface with the or each
sealing surface and thereby restrict flow of fluid through the fluid pathway.
[0011] In some embodiments, the minimum of spacing between the annular valve member and
the guide means is between the guide means and a part of the guide engaging surface
region. The minimum of spacing between the annular valve member and the guide means
may be between the guide means and a said seat-engaging surface.
[0012] In some embodiments the spacing between the guide means and the annular valve member
increases monotonically with distance along the central axis from the minimum of spacing.
[0013] In some embodiments, the spacing between the guide means and the annular valve member
increases non-monotonically with distance along the central axis from the minimum
of spacing.
[0014] In some embodiments, the spacing between the guide means and the annular valve member
increases discontinuously with distance along the central axis from the minimum of
spacing. For example, the guide engaging surface region may comprise a plurality of
surfaces of the annular valve member. In some embodiments, the spacing between the
guide means and the annular valve member may have more than one local minimum and/or
maximum (in relation to axial distance from the said minimum of spacing), when the
annular valve member and the annular valve seat are coaxial.
[0015] The annular valve and annular valve member may be circularly symmetric, or may be
oval or ovoid. The guide engaging surface region may comprise one or more guide engaging
surfaces arranged generally circularly around the axis of symmetry, but having a profile
adapted to cooperate with the guide means (e.g. to permit the annular valve member
to move slideably along the central axis, and in some embodiments to permit a degree
of motion perpendicular to the central axis).
[0016] Thus, in embodiments wherein the annular valve member is located around the guide
means, the diameter of the guide-engaging surface region increases with distance along
the axis of symmetry from the minimum inner circumference (and may increase monotonically,
non-monotonically, continuously or discontinuously). In some embodiments, the annular
valve member may be located within the guide means, and the diameter of the guide-engaging
surface region may decrease (monotonically, non-monotonically, continuously or discontinuously)
with distance along the axis of symmetry from the maximum outer circumference.
[0017] Accordingly, an annular valve member for a face sealing annular valve of a fluid
working machine is also disclosed, the annular valve member being arranged around
an axis of symmetry and comprising a guide engaging surface region extending around
a circumference of the annular valve member for engagement around (or within) cylindrically
arranged guide means of a valve body of a face sealing annular valve for a fluid working
machine; wherein the diameter of the guide-engaging surface region increases (or decreases)
(monotonically, non-monotonically, continuously or discontinuously) with distance
along the axis of symmetry from a minimum inner (or maximum outer) diameter of the
annular valve member.
[0018] In some examples, a said seat-engaging surface extends (preferably smoothly) to a
guide-engaging surface.
[0019] In some examples, at least part of the guide engaging surface region has a tapered
diameter, the diameter increasing (or decreasing) with distance from a minimum inner
(or maximum outer) diameter of the annular valve member, along the axis of symmetry,
i.e. such that the spacing between the guide means and the guide engaging surface
region increases with distance from the minimum of spacing between the annular valve
member and the guide means, when the annular valve member and the annular valve seat
are coaxial.
[0020] The guide engaging surface region provides clearance between the annular valve member
and the guide means, so as to reduce the risk of jamming when the valve member is
tilted out of a plane perpendicular to the central axis (or receives forces which
act to urge the valve member out of a plane perpendicular to the central axis). Thus
the guide engaging surface region is shaped/configured such that the spacing between
the guide means and the guide engaging surface region increases with distance from
the minimum of spacing, which renders the annular valve member of the present invention
more tolerant to tilting away from a plane perpendicular to the central axis (or to
forces applied unevenly around the valve member which might otherwise cause the valve
member to jam), than known annular valve members.
[0021] Preferably, a said seat-engaging surface and a said guide-engaging surface (of the
guide engaging surface region) each extend smoothly to a convex (in radial cross section)
surface extending around the annular valve member. Thus the surface of a radial cross
section of the annular valve member extends from a guide-engaging surface and a seat-engaging
surface to a convex surface. The convex surface may be a radiused surface. In some
examples, some or all of the guide engaging surface region is convex in radial cross
section, and may be radiused, and may be an extension of the radiused surface.
[0022] The guide means may be secured directly or indirectly to the annular valve seat,
or the guide means and the annular valve seat may each be parts of a unitary construction
(i.e. formed from a single piece of material) and the body may be of unitary construction.
[0023] In some embodiments, the guide means consists of a cylindrical guide.
[0024] Preferably, the annular valve member is loosely retained by the guide means. By loosely
retained, we mean that the circumference of the guide means and the circumference
extending around the corresponding surface or surfaces of the annular valve member
differ by more than normal manufacturing tolerances. For example, the annular valve
member may be retained around guide means (such as a cylindrical guide) and be provided
with a guide engaging surface (or surfaces), the minimum inner circumference of which
is slightly larger than the circumference around the guide means. Typically, the circumferences
of the guide means and the respective part or parts of the annular valve member differ
by at least 0.1%, in some embodiments at least 0.5%, and in some embodiments by at
least 2%.
[0025] Thus, the minimum distance between the annular valve member and the guide means,
when the annular valve member and guide means are coaxial, is in some embodiments
at least 0.1%, in some embodiments at least 0.5%, and in some embodiments by at least
2%, of the diameter of the guide means.
[0026] The radial motion of a loosely retained annular valve is restricted by the guide
means, such that the annular valve member and the annular valve seat are sufficiently
well aligned to allow the formation of an effective seal by axial motion of the valve
member, so as to close the valve, whilst maintaining sufficient clearance between
the guide means and the annular valve member to further reduce the risk of jamming
when the valve member is tilted away from perpendicular to the central axis. The additional
clearance between the valve member and the guide means also reduces the risk of jamming
caused by debris becoming trapped therebetween. A further advantage is that fluid
is able to pass between the valve member and the guide means, thereby reducing drag
and friction forces, and facilitating extremely rapid and efficient operation of the
valve.
[0027] Conventional annular valve members are sized to closely engage (within manufacturing
tolerances) with guide means. Such valve members are intolerant to tilting in relation
to the guide means and the valve seat (i.e. in relation to an axis extending through
the valve) and are typically provided with an extended "collar" and the valve with
similarly extended guide means, in order to maintain alignment of the valve member.
Such annular valve members must therefore have a comparatively high L/D ratio (typically
in the range of 0.5 - 0.7), with concomitantly high mass, inertia and drag. By L/D
we mean the ratio between the length of the valve member along its axis of symmetry
and the diameter of the guide engaging formation (for example the internal diameter
of an annular valve member of a valve having a cylindrical guide, around which the
annular valve is slideably mounted).
[0028] A still further advantage of a loosely retained annular valve member which is tolerant
to tilting away from the central axis, is therefore that the valve member may be constructed
having a far smaller L/D ratio (of less than 0.5, and in some embodiments in the region
of 0.1, or less than 0.1). Consequently, the annular valve member is also lighter
than those of known annular valves, and may therefore be operated more rapidly, and
is also much shorter, and therefore provides for a much more compact valve.
[0029] Preferably, the annular valve further comprises an end stop, to limit the maximum
amount of axial motion of the annular valve member away from the annular valve seat.
[0030] In some examples, the end stop extends from the guide means. The end stop may be
secured to the guide means (and for example may be a collar secured about or within
the guide means), or the end stop may be integral to the guide means.
[0031] Preferably, the angle of tilt (away from perpendicular to the central axis) of the
annular valve member is limited by the axial distance between the annular valve seat
and the end stop. i.e. the axial distance between the axial valve seat and the end
stop is preferably such that the annular valve member may tilt so as to abut the end
stop and the guide means, or the end stop and the annular valve seat, but has insufficient
room to contact the guide means at any two opposite sides of the guide means (that
is to say points on each of the lines at which a plan extending through the central
axis intersects the guide means) (which may otherwise cause the annular valve member
to jam against the guide means).
[0032] That is to say, as a result of an annular valve member having an annular valve member
which is loosely retained by guide means, the annular valve member is free to tilt
in relation to the central axis (and also to move radially with respect to the central
axis), out of alignment with the valve seat and the guide means;
and when a part of the annular valve member (typically a said seat-engaging surface)
is in contact (sealedly or otherwise) with the annular valve seat (typically a said
sealing surface), and a part of the annular valve member (typically the guide-engaging
surface region) on the opposite side of the central axis is in contact with the end
stop or the guide means, i.e. when the annular valve member has the maximum amount
of tilt possible, the annular valve member cannot simultaneously contact the guide
means on diametrically opposite sides of the guide means.
[0033] Preferably, the minimum distance L between the annular valve member and the guide
means, when the annular valve member and the annular valve seat are coaxial and the
annular valve member is oriented perpendicular to the central axis is given by:

where G is the diameter of the guide means and theta is the maximum angle of tilt
of the annular valve member out of a plane perpendicular to the central axis, when
a part of the annular valve member is in contact with the annular valve seat and a
part of the annular valve member is in contact with the end stop.
[0034] Thus, the maximum angle of tilt theta is approximately theta = tan
-1(M/G), where M is the maximum length of movement that the annular valve member is
free to move along the central axis (i.e. between positions where the annular valve
member abuts the end stop and the sealing surface), and G is the diameter of the guide
means.
[0035] Of an annular valve member retained (or adapted to be retained) around guide means,
no part of the annular valve member falls within a region defined by frusta extending
from the minimum inner circumference at an angle equal to or less than theta away
from the axis of symmetry of the annular valve member, wherein theta is the maximum
angle that the annular valve member is free to tilt out of a plane perpendicular to
the central axis (when the annular valve member is retained around the guide means).
[0036] Similarly, of an annular valve member retained (or adapted to be retained) within
guide means, no part of the annular valve member falls within a region defined by
frusta extending from the maximum outer circumference at an angle equal to or less
than theta away from the axis of symmetry of the annular valve member, wherein theta
is the maximum angle that the annular valve member is free to tilt out of a plane
perpendicular to the central axis (when the annular valve member is retained within
the guide means).
[0037] Thus, a frustrum extending between the minimum inner (or maximum outer, as the case
may be) circumference of the annular valve member and any other part of the guide
engaging surface region (or other part of the annular valve member, such as any part
of the or each said seat engaging surface) extends at an angle greater than theta
away from the axis of symmetry of the annular valve member.
[0038] It may be that no part of the annular valve member falls within a region defined
by frusta extending through a ring in the plane of the minimum of spacing when the
annular valve member and annular valve seat are coaxial and having a diameter G+2L,
the frusta having an axis coincident with the axis of symmetry of the annular valve
member and a conical angle of 2theta.
[0039] Preferably, a part of the guide engaging surface region comprises the minimum inner
(or maximum outer) circumference of the annular valve member.
[0040] In some embodiments, the valve seat comprises a first sealing surface having a first
circumferential dimension and a second sealing surface having a second circumferential
dimension, and wherein the or each said aperture is between the first and second sealing
surface, the annular valve member comprising a first seat-engaging surface for cooperative
engagement with the first sealing surface, and a second seat-engaging surface for
cooperative engagement with the second sealing surface.
[0041] In some embodiments, the annular valve member is elastically deformable between a
relaxed configuration in which the first seat-engaging surface is sized to sealedly
engage with the first sealing surface and the second seat-engaging surface is disposed
in relation to the first seat-engaging surface such that the second sealing surface
and the second seat-engaging surface do not sealedly engage when the first sealing
surface and the first seat-engaging surface are in sealing engagement; and a deformed
configuration in which the second sealing surface and the second seat-engaging surface
are in sealing engagement while the first sealing surface and the first seat-engaging
surface are in sealing engagement, thereby restricting flow of fluid through the fluid
pathway.
[0042] The annular valve member may be resiliently biased towards (or, in some embodiments,
away from) the annular valve seat by resilient biasing means (such as a coiled spring).
[0043] Alternatively, or in addition, the annular valve member may be controllably urged
away from (or towards) the annular valve seat by electronically controllable urging
means, for example an electromagnet (typically secured to, or forming a part of, the
body).
[0044] A portion of the body may, in some embodiments, define a cylinder adapted to receive
a reciprocating piston (of a fluid working machine), and a portion of an external
surface of the cylinder walls define the cylindrical guide for the annular valve member.
[0045] Thus, the invention extends in a third aspect to a cylinder assembly comprising an
annular valve according to the first aspect, wherein the body defines a cylinder adapted
to receive a reciprocating piston of a fluid working machine.
[0046] By a circumference we refer to the distance within or around respectively an interior
or exterior surface. The first and second annular sealing surfaces, internal and external
surfaces of the annular valve member, and the annular valve member itself, are typically
rotationally symmetric but some departure from rotational symmetry is possible.
Brief Description of Drawings
[0047] An example embodiment of the present invention will now be illustrated with reference
to the following Figures in which:
[fig.1]Figure 1 is a cross sectional view of a cylinder assembly;
[fig.2]Figure 2 is a cross-section through one side of an annular valve, when the
annular valve member is in a position in which its axis is coincident with the axis
of the annular valve seat and the cylinder axis;
[fig.3]Figure 3 is a cross-section through one side of the annular valve of Figure
2, with the annular valve member displaced radially inwards;
[fig.4]Figure 4 is a cross-section through one side of the annular valve of Figure
2, with the annular valve member tilted in one sense;
[fig.5]Figure 5 is a cross-section through one side of the annular valve of Figure
2, with the annular valve member tilted in the other sense;
[fig.6]Figure 6 is a cross-section through the annular valve of Figure 2;
[fig.7]Figure 7 is a cross-section through the annular valve of Figure 2, with the
annular valve member tilted in the sense of Figure 5;
[fig.8A]Figure 8A is a cross-section through one side of the annular valve of Figure
2;
[fig.8B]Figure 8B is a cross-section through one side of an alternative embodiment
of an annular valve;
[fig.8C]Figure 8C is a cross-section through one side of an alternative embodiment
of an annular valve;
[fig.8D]Figure 8D is a cross-section through one side of an alternative embodiment
of an annular valve; and
[fig.9]Figure 9 is a cross-section through one side of an alternative embodiment of
an annular valve.
Description of Embodiments
[0048] Figure 1 shows a cylinder assembly 1 for use with a fluid-working machine, such as
a hydraulic pump, a hydraulic motor or a hydraulic pump-motor. The cylinder assembly
comprises a body 2 which is generally cylindrically symmetric around the cylinder
axis A and comprises a cylinder 3 which is open to a first end 4 of the body, a poppet
valve seat 5, located at a second end 6 of the body, and defining a poppet valve aperture
7 (providing a fluid pathway between the cylinder and radial passages 9 extending
through an upper portion of the body), and an annular valve seat 11, defining a plurality
of apertures 13 arrayed around and extending through the body. The annular valve seat
comprises an outer sealing surface 15 and an inner sealing surface 17.
[0049] An annular valve member 19 is retained around the body between the annular valve
seat and the end stop 21 of a collar 23. The annular valve member is threaded around
the outer surface of the cylinder at a cylindrical guide surface region 25 of the
cylinder. The guide surface region of the cylinder takes the form of a cylindrical
guide and functions as guide means for the annular valve member.
[0050] The annular valve regulates the flow of hydraulic fluid between a high pressure manifold
27 and the cylinder, by way of the apertures 13. The annular valve member is biased
towards the annular valve seat by coiled spring 29 which extends between the lower
face 31 of the annular valve member and an opposed upper face 33 of the collar. The
annular valve member has a seat engaging surface 34 for forming the inner and outer
seals between the annular valve member and the annular valve seat. The collar is held
in place by retaining ring 35. The collar may be provided with an interference fit
around the cylinder for a part, or all, of the depth of the collar or the collar and
cylinder body may be cooperatively engaged, for ease of installation and removal of
the collar, annular high pressure valve and spring.
[0051] The assembly further comprises a poppet valve member 37 which, together with the
poppet valve seat and poppet valve aperture, forms a poppet valve for controlling
the flow of fluid between radial passages 9 (which are in fluid communication with
a low pressure manifold 39) and the cylinder 5. The poppet valve member is operable
to move along the axis A, such that the poppet valve may be moved between an open
position (as shown) and a closed position where the sealing surface 41 (an annular
region on an upper face of the head portion 43 of the poppet valve member) is in contact
with the poppet valve seat.
[0052] The poppet valve member is provided at its lower end with a peg 45, which is in slideable
engagement with a central aperture 47 in lower guide structure 49. The lower guide
structure comprises and is held in place by radial struts 51 extending to the inner
walls of the cylinder and, in use, functions to restrict movement of the peg away
from the cylinder axis and to form a partial barrier to protect or isolate fluid flow
between the cylinder and the low pressure manifold from the poppet, which would otherwise
act to urge the poppet valve closed.
[0053] At its upper end, the poppet valve member is provided with an armature 53, comprising
passages 55 extending between upper and lower faces of the armature, placing radial
passages 39 in fluid communication with coil space 57 around which is located a solenoid
coil 59, enabling the poppet valve to be electronically actuated by control signals
from an electronic controller (not shown). The outer face of the armature is slidably
engaged with the inner face 61 of upper guide structure 63. A first seal, 65, extends
around a channel provided in the collar, and second and third seal 67, 69 extend around
similar channels provided in the body, above the annular valve seat. The first and
second seals prevent egress of pressurised hydraulic fluid from the high pressure
manifold around the cylinder assembly during operation.
[0054] In contrast to the actively controlled poppet valve, in the present example the annular
valve member is a passively opening and closing face sealing valve. The spring biases
the annular valve member towards the annular valve seat. When the pressure within
the cylinder is greater than the pressure in the high pressure manifold, the annular
valve opens (as shown in Figure 1) to enable hydraulic fluid to be exhausted from
the cylinder to the high pressure manifold. When the pressure within the high pressure
manifold is greater than the pressure in the cylinder, the annular valve member seals
against the both the inner and outer sealing surfaces, forming a seal. In the example
shown, the annular valve member is made from a resilient material and after contacting
the outer sealing surface, the annular valve member deforms to enable the annular
valve member to also form the inner seal. However, the invention is also applicable
to annular valve members of which only a part is resilient, or which are rigid.
[0055] The annular valve member has an axis of circular symmetry which, in Figure 1, is
coincident with the cylinder axis A and the axis of the annular valve seat. The invention
also extends to embodiments in which the cylinder axis and the axis of the annular
valve seat are different. However, the annular valve member is loosely retained on
the guide means, such that there can be a small amount of tilting of annular valve
member relative to the cylinder and annular valve seat, and there can also be a small
amount of radial movement of the annular valve member.
[0056] Figure 2 illustrates the annular valve member in a position in which its axis is
coincident with the axis of the annular valve seat and the cylinder axis. The annular
valve member has a guide-engaging surface region 71. The spacing between the guide-engaging
surface region and the guide surface region of the cylinder (i.e. the radial distance
between the guide surface region of the cylinder and the overlying radially inward
surface of the guide-engaging surface region) varies in an axial direction and there
is a minimum 73 of spacing when the axes of the annular valve member and the annular
valve seat are coincident. To either side of the minimum of spacing, the spacing between
the annular valve member and the guide surface region of the cylinder increases.
[0057] Figure 3 shows the annular valve displaced radially inwards at the point through
which the cross-section has been taken (the opposite side of the annular valve will
be displaced radially by the same amount). Figure 4 shows the annular valve tilted
in one sense until it contacts the annular valve seat and Figure 5 shows the annular
valve tilted in the opposite sense until it contacts the end stop.
[0058] Figure 6 shows opposite side of the annular valve in the configuration of Figure
2 and Figure 7 shows opposites sides of the annular valve in the configuration of
Figure 5. With reference to these figures, G is the diameter of the guide surface
region of the cylinder and L is the spacing between the guide surface region and the
guide-engaging surface region at the minimum of spacing (in each case, when the annular
valve member and annular valve seat are coaxial).
[0059] At maximum tilt, the annular valve member may contact the end stop on one side and
either guide surface region or the annular valve seat on the other, or may contact
the annular valve seat on one side and the guide surface region on the other side.
However, it can be seen that the axial extent of the annular valve member and the
spacing between the end stop and the annular valve seat are configured such that the
annular valve member cannot tilt sufficiently to contact the guide surface region
simultaneously at two diametrically opposite sides of the annular valve member. This
avoids the possibility of the annular valve member jamming by contacting the guide
surface region simultaneously on diametrically opposite sides. In Figure 7, theta
represents the maximum angle which it is possible for the annular valve member to
tilt relative to the axis of the annular valve seat.
[0060] As the maximum angle of tilt, theta, is such that the annular valve member cannot
contact the guide surface region simultaneously at two diametrically opposite sides
of the annular valve member , L, the minimum distance between the annular valve member
and the guide surface region (when the annular valve member and annular valve seat
are coaxial) fulfils the following relationship:

[0061] Thus, the maximum angle of tilt theta is approximately theta = tan
-1(M/G), where M is the maximum distance which the annular valve member is free to move
along the central axis, M, which is the sum of m
1 and m
2 shown in Figure 6.
[0062] With reference to Figure 8A, in order to ensure that there cannot be jamming, while
still providing a compact annular valve, it is preferred that no part of the annular
valve member extends into the volume defined by virtual frusta 75, 77 which are coaxial
with the annular valve member, extending from the minimum of spacing at an angle of
theta to the axis of the annular valve member. In this embodiment, no part of the
annular valve member falls within a region defined by frusta extending through a ring
having a diameter G+2L, an axis coincident with the axis of symmetry of the annular
valve member and a conical angle of 2theta.
[0063] The annular valve of the invention is advantageous in that it has a sufficiently
small internal diameter to restrict the radial motion of the annular valve member
enough to enable an effective seal to be reliably formed, but without jamming when
the valve member is tilted. There is sufficient space to reduce the risk of jamming
resulting from trapped debris.
[0064] The design is also such that drag and friction acting on the annular valve member
are low, allowing rapid and energy efficient operation of the annular valve. This
arises as there is only one guiding line, rather than two guiding lines spaced a significant
distance apart in known annular valves mounted on a guide, which has at least some
sliding length. Known annular valves typically involve a tightly fitting collar around
a guide, with a thin oil film between, which generates shear drag.
[0065] Furthermore, the design is sufficiently strong to withstand the stresses from high
pressure oil acting on it.
[0066] Figure 8B is a cross-section through an annular valve of an alternative embodiment,
in which the outer sealing surface extends orthogonally to the axis of the annular
valve seat. The angle of the outer sealing surface can vary between embodiments, for
example it may extend at an angle of 30° to 90° from the axis of the annular valve
seat (coincident with cylinder axis A in this embodiment). For example, the outer
sealing surface may extend at an angle of 30° to 90° from the axis of the annular
valve seat. In this embodiment, a length of the guide-engaging surface region has
the same diameter and so the minimum of spacing has an axial extent. The frusta extend
from either end of the minimum of spacing.
[0067] Figure 8C is a cross-section through an annular valve of an alternative embodiment
in which the apertures 7 do not intersect the outer surface of the cylinder but instead
open only onto an outward extending peripheral surface 79 of the cylinder body including
the outer sealing surface, which extends at an obtuse angle to the outer surface of
the cylinder. In this embodiment, the spacing of the guide-engaging surface changes
discontinuously from the minimum of spacing to a higher diameter surface region 81.
[0068] Figure 8D is a cross-section through an annular valve of an alternative embodiment
in which the apertures 7 open onto an outwardly extending peripheral surface of the
cylinder body, including both the inner 17 and the outer 15 sealing surface, which
extends orthogonally to the axis of annular valve seat. In this embodiment, the inner
and outer sealing surfaces are in the same plane, orthogonal to the axis of the annular
valve seat. In this embodiment, the annular valve member has inner and outer circumferential
ridges 83, 85 which extends axially from the seat facing surface 87 of the annular
valve member to form the inner and outer seals in use. In this case, instead of the
inner seal being formed by part of the guide-engaging surface of the annular valve
member, the guide-engaging surface of the annular valve member includes a guiding
formation 89, which also functions as the minimum of spacing. In this embodiment,
the spacing of the guide-engaging surface increase monotonically, but with a varying
gradient, away from the minimum of spacing.
[0069] In the illustrated examples, the outer surface of the cylinder functions as guide
means for the annular valve member. However, alternatively, it would be possible for
one or more guide members, arranged in a cylinder, and extending through the annular
valve member to function as guide means. In some alternative embodiments, the guide
means could be located outside the annular valve member.
[0070] Figure 9 is a cross-section through an annular valve of an alternative embodiment
in which the annular valve member 100 has a planar seat contacting surface 101. The
inner and outer seals are formed by inner and outer circumferential ridges 103, 105
on an outwardly extending peripheral surface 79.
[0071] Further variations and modifications may be made within the scope of the invention
herein disclosed.
Reference Signs List
[0072]
1 Cylinder assembly
2 Body
3 Cylinder
4 First end of cylinder
5 Poppet valve seat
6 Second end of cylinder
7 Poppet valve aperture
9 Radial passages
11 Annular valve seat
13 Apertures
15 Outer sealing surface
17 Inner sealing surface
19 Annular valve member
21 End stop
23 Collar
25 Guide surface region (guide means)
27 High pressure manifold
29 Spring
31 Lower face of annular valve member
33 Upper face of collar
34 Seat engaging surface
35 Retaining ring
37 Poppet valve member
39 Low pressure manifold
41 Sealing surface
43 Head portion
45 Peg
47 Central aperture
49 Lower guide structure
51 Radial struts
53 Armature
55 Passages
57 Coil space
59 Solenoid
61 Inner face
63 Upper guide structure
65 First seal
67 Second seal
69 Third seal
71 Guide-engaging surface region
73 Minimum of spacing
75 Virtual frustrum
77 Virtual frustrum
79 Peripheral surface
81 Higher diameter surface region
83 Inner circumferential ridge
85 Outer circumferential ridge
87 Seat facing surface
89 Guiding formation
100 Annular valve member
101 Seat contacting surface
103 Inner circumferential ridge
105 Outer circumferential ridge
1. A face sealing annular valve for a fluid working machine, the valve having a valve
body arranged around a central axis and comprising an annular valve seat (11) and
guide means (25), and an annular valve member (19) located around or within the guide
means;
the guide means comprising one or more cylindrically arranged guides to restrict radial
motion of the annular valve member, the guide means being configured loosely to retain
the annular valve member around or within the guide means so that the annular valve
member is free to tilt out of a plane perpendicular to the central axis within a maximum
tilt angle;
the annular valve member arranged around an axis of symmetry and moveable axially
in relation to the guide means to sealedly engage with the annular valve seat; and
a guide engaging surface region (71) extending around a circumference of the annular
valve member;
wherein the annular valve member has a minimum inner circumference or maximum outer
circumference at which the guide engaging surface region of the annular valve member
faces the guide means across a minimum spacing between the annular valve member and
the guide means,
wherein the annular valve member is configured so that, when the annular valve member
and the annular valve seat are coaxial, the spacing between the guide means and the
guide-engaging surface region increases with distance along the central axis from
the minimum spacing at the minimum inner circumference or maximum outer circumference,
and
characterized in that the annular valve member is configured such that no part of the annular valve member
falls within a region defined by frusta extending from the minimum inner circumference
or maximum inner circumference at an angle equal to the maximum tilt angle away from
the axis of symmetry.
2. An annular valve according to claim 1, wherein the spacing between the guide means
and the annular valve member increases monotonically with distance along the central
axis from the minimum of spacing.
3. An annular valve according to claim 1, wherein the guide means consists of a cylindrical
guide.
4. An annular valve according to claim 1, wherein the annular valve further comprises
an end stop (21), to limit the maximum amount of axial motion of the annular valve
member away from the annular valve seat.
5. An annular valve according to claim 4, wherein the maximum angle of tilt of the annular
valve member in relation to the central axis is limited by the axial distance between
the annular valve seat and the end stop.
6. An annular valve according to claim 5, wherein the annular valve member is configured
to be loosely retained by the guide means so that, when the annular valve member tilts
relative to the guide means by the maximum tilt angle, the annular valve member cannot
simultaneously contact the guide means on diametrically opposite sides of the guide
means which are on a line extending through the central axis.
7. An annular valve according to claim 6, wherein the minimum distance L between the
annular valve member and the guide means, when the annular valve member and the annular
valve seat are coaxial and the annular valve member is oriented perpendicular to the
central axis is given by:

where G is the diameter of the guide means and theta is the maximum tilt, when a
part of the annular valve member is in contact with the annular valve seat and a part
of the annular valve member is in contact with the end stop.
8. An annular valve according to claim 7, wherein no part of the annular valve member
falls within a region defined by frusta extending through a ring in the plane of the
minimum of spacing when the annular valve member and annular valve seat are coaxial
and having a diameter G+2L, the frusta having an axis coincident with the axis of
symmetry of the annular valve member and a conical angle of 2theta.
9. An annular valve according to claim 1, having cylindrical guide means, wherein a portion
of the body defines a cylinder adapted to receive a reciprocating piston, and wherein
a portion of an external surface of the cylinder walls define the cylindrical guide
for the annular valve member.
10. An annular valve according to claim 1, wherein the annular valve member is retained
around guide means and wherein the diameter of the guide-engaging surface region increases
with distance along the axis of symmetry from a minimum inner diameter of the annular
valve member.
11. An annular valve member for a face sealing annular valve according to claim 1; the
annular valve member arranged around an axis of symmetry and comprising a guide engaging
surface region extending around a circumference of the annular valve member for engagement
around cylindrically arranged guide means of a face sealing annular valve for a fluid
working machine;
wherein the diameter of the guide-engaging surface region increases with distance
along the axis of symmetry from a minimum inner diameter of the annular valve member,
wherein the annular valve member has a minimum inner circumference or maximum outer
circumference at which, when the annular valve member is in use, the guide engaging
surface region of the annular valve member faces the guide means across a minimum
spacing between the annular valve member and the guide means,
wherein the annular valve member is configured so that, when the annular valve member
and the annular valve seat are coaxial, the spacing between the guide means and the
guide-engaging surface region increases with distance along the central axis from
the minimum spacing at the minimum inner circumference or maximum outer circumference,
and
characterized in that the annular valve member is configured such that no part of the annular valve member
falls within a region defined by frusta extending from the minimum inner circumference
or maximum inner circumference at an angle equal to the maximum tilt angle away from
the axis of symmetry.
1. Ringförmiges Gesichtsabdichtungsventil für eine Fluidarbeitsmaschine, wobei das Ventil
einen Ventilkörper aufweist, der um eine zentrale Achse angeordnet ist, und einen
ringförmigen Ventilsitz (11) und Führungsmittel (25) und ein ringförmiges Ventilelement
(19) umfasst, das um oder innerhalb der Führungsmittel angeordnet ist;
wobei die Führungsmittel eine oder mehrere zylindrisch angeordnete Führungen zum Begrenzen
der Bewegung des ringförmigen Ventilelements umfassen, wobei die Führungsmittel zum
losen Halten des ringförmigen Ventilelements um oder innerhalb der Führungsmittel
konfiguriert sind, damit das ringförmige Ventilelement frei aus einer Ebene kippen
kann, die senkrecht zur zentralen Achse innerhalb eines maximalen Neigungswinkels
verläuft;
wobei das ringförmige Ventilelement um eine Symmetrieachse angeordnet ist und axial
in Bezug auf die Führungsmittel zum dichtenden Eingreifen mit dem ringförmigen Ventilsitz
beweglich ist; und
einen Führungseingriff-Oberflächenbereich (71), der sich um einen Umfang des ringförmigen
Ventilelements erstreckt;
wobei das ringförmige Ventilelement einen minimalen Innenumfang oder maximalen Außenumfang
aufweist, an denen der Führungseingriff-Oberflächenbereich des ringförmigen Ventilelements
zu den Führungsmitteln über einen Mindestabstand zwischen dem ringförmigen Ventilelement
und den Führungsmitteln weist,
wobei das ringförmige Ventilelement derart konfiguriert ist, dass, wenn das ringförmige
Ventilelement und der ringförmige Ventilsitz koaxial verlaufen, der Abstand zwischen
den Führungsmitteln und dem in die Führung eingreifenden Oberflächenbereich mit dem
Abstand entlang der zentralen Achse von dem Mindestabstand am minimalen Innenumfang
oder maximalen Außenumfang zunimmt, und
dadurch gekennzeichnet, dass das ringförmige Ventilelement derart konfiguriert ist, dass kein Teil des ringförmigen
Ventilelements innerhalb eines Bereichs fällt, der von einem Kegelstumpf definiert
wird, der sich von dem minimalen Innenumfang oder dem maximalen Innenumfang in einem
Winkel erstreckt, der dem maximalen abgehenden Neigungswinkel von der Symmetrieachse
entspricht.
2. Ringförmiges Ventil nach Anspruch 1, wobei der Abstand zwischen den Führungsmitteln
und dem ringförmigen Ventilelement monoton mit dem Abstand entlang der zentralen Achse
vom Mindestabstand zunimmt.
3. Ringförmiges Ventil nach Anspruch 1, wobei das Führungsmittel aus einer zylindrischen
Führung besteht.
4. Ringförmiges Ventil nach Anspruch 1, wobei das ringförmige Ventil ferner einen Endanschlag
(21) umfasst, um die maximale Menge der axialen Bewegung des ringförmigen Ventilelements,
das dem ringförmigen Ventilsitz abgewandt ist, zu begrenzen.
5. Ringförmiges Ventil nach Anspruch 4, wobei der maximale Neigungswinkel des ringförmigen
Ventilelements in Bezug auf die zentrale Achse durch den axialen Abstand zwischen
dem ringförmigen Ventilsitz und dem Endanschlag begrenzt wird.
6. Ringförmiges Ventil nach Anspruch 5, wobei das ringförmige Ventilelement so konfiguriert
ist, um lose von den Führungsmitteln gehalten zu werden, sodass, wenn sich das ringförmige
Element in Bezug auf die Führungsmittel über den maximalen Neigungswinkel neigt, das
ringförmige Ventilelement nicht gleichzeitig mit den Führungsmitteln auf im Durchmesser
gegenüberliegenden Seiten der Führungsmittel damit in Kontakt treten kann, die auf
einer Linie liegen, die sich durch die zentrale Achse erstreckt.
7. Ringförmiges Ventil nach Anspruch 6, wobei der minimale Abstand L zwischen dem ringförmigen
Ventilelement und den Führungsmitteln, wenn das ringförmige Ventilelement und der
ringförmige Ventilsitz koaxial zueinander verlaufen und das ringförmige Ventilelement
senkrecht zur zentralen Achse ausgerichtet ist, wie folgt gegeben ist:

worin G der Durchmesser der Führungsmittel ist und theta die maximale Neigung, wenn
ein Teil des ringförmigen Ventilelements in Kontakt mit dem ringförmigen Ventilsitz
ist und ein Teil des ringförmigen Ventilelements in Kontakt mit dem Endanschlag ist.
8. Ringförmiges Ventil nach Anspruch 7, wobei kein Teil des ringförmigen Ventilelements
innerhalb eines Bereichs fällt, der durch den Kegelstumpf definiert wird, der sich
durch einen Ring auf der Ebene des Mindestabstands erstreckt, wenn das ringförmige
Ventilelement und der ringförmige Ventilsitz koaxial verlaufen und einen Durchmesser
G+2L aufweist, wobei der Kegelstumpf eine Achse aufweist, die der Symmetrieachse des
ringförmigen Ventilelements und einem Kegelwinkel von 2xtheta entspricht.
9. Ringförmiges Ventil nach Anspruch 1, aufweisend zylindrische Führungsmittel, wobei
ein Abschnitt des Körpers einen Zylinder definiert, der zum Aufnehmen eines hin- und
hergehenden Kolbens ausgelegt ist, und wobei ein Abschnitt einer äußeren Oberfläche
der Zylinderwände die zylindrische Führung für das ringförmige Ventilelement definiert.
10. Ringförmiges Ventil nach Anspruch 1, wobei das ringförmige Ventilelement um die Führungsmittel
gehalten wird und wobei der Durchmesser des in die Führung eingreifenden Oberflächenbereichs
mit dem Abstand entlang der Symmetrieachse von einem minimalen inneren Durchmesser
des ringförmigen Ventilelements zunimmt.
11. Ringförmiges Ventilelement für ein ringförmiges Gesichtsabdichtungsventil nach Anspruch
1, wobei das ringförmige Ventilelement, das um eine Symmetrieachse angeordnet ist
und einen in eine Führung eingreifenden Oberflächenbereich umfasst, der sich um einen
Umfang des ringförmigen Ventilelements um zylindrisch angeordnete Führungsmittel eines
ringförmigen Gesichtsabdichtungsventils für eine Fluidarbeitsmaschine erstreckt;
wobei der Durchmesser des in die Führung eingreifenden Oberflächenbereichs mit dem
Abstand entlang der Symmetrieachse von einem minimalen Innendurchmesser des ringförmigen
Ventilelements zunimmt,
wobei das ringförmige Ventilelement einen minimalen Innenumfang oder maximalen Außenumfang
aufweist, an dem, wenn das ringförmige Ventilelement in Gebrauch ist, der Führungseingriff-Oberflächenbereich
des ringförmigen Ventilelements zu den Führungsmitteln über einen Mindestabstand zwischen
dem ringförmigen Ventilelement und den Führungsmitteln weist,
wobei das ringförmige Ventilelement derart konfiguriert ist, dass, wenn das ringförmige
Ventilelement und der ringförmige Ventilsitz koaxial verlaufen, der Abstand zwischen
den Führungsmitteln und dem in die Führung eingreifenden Oberflächenbereich mit dem
Abstand entlang der zentralen Achse von dem Mindestabstand am minimalen Innenumfang
oder maximalen Außenumfang zunimmt, und
dadurch gekennzeichnet, dass das ringförmige Ventilelement derart konfiguriert ist, dass kein Teil des ringförmigen
Ventilelements innerhalb eines Bereichs fällt, der von einem Kegelstumpf definiert
wird, der sich von dem minimalen Innenumfang oder dem maximalen Innenumfang in einem
Winkel erstreckt, der dem maximalen abgehenden Neigungswinkel von der Symmetrieachse
entspricht.
1. Soupape annulaire à étanchéité frontale pour une machine de travail hydraulique, la
soupape comprenant un corps de soupape agencé autour d'un axe central et comprenant
un siège de soupape annulaire (11) et des moyens de guidage (25), et un élément de
soupape annulaire (19) situé autour ou à l'intérieur des moyens de guidage;
les moyens de guidage comprenant un ou plusieurs guide(s) agencé(s) de façon cylindrique
afin de limiter le mouvement radial de l'élément de soupape annulaire, les moyens
de guidage étant configurés librement pour retenir l'élément de soupape annulaire
autour ou à l'intérieur des moyens de guidage de telle sorte que l'élément de soupape
annulaire soit libre de s'incliner hors d'un plan perpendiculaire à l'axe central
à l'intérieur d'un angle d'inclinaison maximum;
l'élément de soupape annulaire étant agencé autour d'un axe de symétrie et étant mobile
axialement par rapport aux moyens de guidage afin de s'engager de façon étanche avec
le siège de soupape annulaire; et
une région de surface d'engagement de guidage (71) qui s'étend autour d'une circonférence
de l'élément de soupape annulaire,
dans laquelle l'élément de soupape annulaire présente une circonférence intérieure
minimum ou une circonférence extérieure maximum à laquelle la région de surface d'engagement
de guidage de l'élément de soupape annulaire fait face aux moyens de guidage en travers
d'un espacement minimum entre l'élément de soupape annulaire et les moyens de guidage,
dans laquelle l'élément de soupape annulaire est configuré de telle sorte que, lorsque
l'élément de soupape annulaire et le siège de soupape annulaire sont coaxiaux, l'espacement
entre les moyens de guidage et la région de surface d'engagement de guidage augmente
avec la distance le long de l'axe central depuis l'espacement minimum à la circonférence
intérieure minimum ou à la circonférence extérieure maximum, et
caractérisée en ce que l'élément de soupape annulaire est configuré de telle sorte qu'aucune partie de l'élément
de soupape annulaire ne tombe à l'intérieur d'une région définie par un tronc s'étendant
à partir de la circonférence intérieure minimum ou de la circonférence extérieure
maximum avec un angle égal à l'angle d'inclinaison maximum à partir de l'axe de symétrie.
2. Soupape annulaire selon la revendication 1, dans laquelle l'espacement entre les moyens
de guidage et l'élément de soupape annulaire augmente de façon monotone avec la distance
le long de l'axe central à partir du minimum d'espacement.
3. Soupape annulaire selon la revendication 1, dans laquelle les moyens de guidage sont
constitués d'un guide cylindrique.
4. Soupape annulaire selon la revendication 1, dans laquelle la soupape annulaire comprend
en outre un arrêt d'extrémité (21) destiné à limiter la quantité maximum de mouvement
axial de l'élément de soupape annulaire à l'écart du siège de soupape annulaire.
5. Soupape annulaire selon la revendication 4, dans laquelle l'angle d'inclinaison maximum
de l'élément de soupape annulaire par rapport à l'axe central est limité par la distance
axiale entre le siège de soupape annulaire et l'arrêt d'extrémité.
6. Soupape annulaire selon la revendication 5, dans laquelle l'élément de soupape annulaire
est configuré de manière à être retenu librement par les moyens de guidage de telle
sorte que, lorsque l'élément de soupape annulaire s'incline par rapport aux moyens
de guidage avec l'angle d'inclinaison maximum, l'élément de soupape annulaire ne puisse
pas entrer en contact simultanément avec les moyens de guidage sur des côtés diamétralement
opposés des moyens de guidage qui se trouvent sur une ligne qui s'étend à travers
l'axe central.
7. Soupape annulaire selon la revendication 6, dans laquelle la distance minimum L entre
l'élément de soupape annulaire et les moyens de guidage, lorsque l'élément de soupape
annulaire et le siège de soupape annulaire sont coaxiaux et que l'élément de soupape
annulaire est orienté perpendiculairement à l'axe central est donnée par:

dans laquelle G est le diamètre des moyens de guidage et θ est l'inclinaison maximum,
lorsqu'une partie de l'élément de soupape annulaire est en contact avec le siège de
soupape annulaire et qu'une partie de l'élément de soupape annulaire est en contact
avec l'arrêt d'extrémité.
8. Soupape annulaire selon la revendication 7, dans laquelle aucune partie de l'élément
de soupape annulaire ne tombe à l'intérieur d'une région définie par un tronc s'étendant
à travers un anneau dans le plan du minimum d'espacement lorsque l'élément de soupape
annulaire et le siège de soupape annulaire sont coaxiaux et présentant un diamètre
de G+2L, le tronc présentant un axe coïncidant avec l'axe de symétrie de l'élément
de soupape annulaire et un angle conique de 2θ.
9. Soupape annulaire selon la revendication 1, comprenant des moyens de guidage cylindriques,
dans laquelle une partie du corps définit un cylindre apte à recevoir un piston alternatif,
et dans laquelle une partie d'une surface externe des parois du cylindre définit le
guide cylindrique pour l'élément de soupape annulaire.
10. Soupape annulaire selon la revendication 1, dans laquelle l'élément de soupape annulaire
est retenu autour de moyens de guidage, et dans laquelle le diamètre de la région
de surface d'engagement de guidage augmente avec la distance le long de l'axe de symétrie
à partir d'un diamètre intérieur minimum de l'élément de soupape annulaire.
11. Elément de soupape annuaire pour une soupape annulaire à étanchéité frontale selon
la revendication 1; l'élément de soupape annulaire étant agencé autour d'un axe de
symétrie et comprenant une région de surface d'engagement de guidage qui s'étend autour
d'une circonférence de l'élément de soupape annulaire pour un engagement autour de
moyens de guidage agencés de façon cylindrique d'une soupape annulaire à étanchéité
frontale pour une machine de travail hydraulique;
dans lequel le diamètre de la région de surface d'engagement de guidage augmente avec
la distance le long de l'axe de symétrie à partir d'un diamètre intérieur minimum
de l'élément de soupape annulaire,
dans lequel l'élément de soupape annulaire présente une circonférence intérieure minimum
ou une circonférence extérieure maximum à laquelle, lorsque l'élément de soupape annulaire
est en cours d'utilisation, la région de surface d'engagement de guidage de l'élément
de soupape annulaire fait face aux moyens de guidage en travers d'un espacement minimum
entre l'élément de soupape annulaire et les moyens de guidage,
dans lequel l'élément de soupape annulaire est configuré de telle sorte que, lorsque
l'élément de soupape annulaire et le siège de soupape annulaire sont coaxiaux, l'espacement
entre les moyens de guidage et la région de surface d'engagement de guidage augmente
avec la distance le long de l'axe central depuis l'espacement minimum à la circonférence
intérieure minimum ou à la circonférence extérieure maximum, et
caractérisé en ce que l'élément de soupape annulaire est configuré de telle sorte qu'aucune partie de l'élément
de soupape annulaire ne tombe à l'intérieur d'une région définie par un tronc s'étendant
à partir de la circonférence intérieure minimum ou de la circonférence extérieure
maximum avec un angle égal à l'angle d'inclinaison maximum à partir de l'axe de symétrie.